Process for the separation of ketazines from their crude synthesis mixtures

ABSTRACT

This invention relates to a process for the separation by distillation of ketazines from a crude aqueous synthesis mixture containing them, which comprises adjusting the pH of the mixture to between about 8.5 and 12 by the addition of a base or an acid and distilling the crude reaction mixture during a period of 30 minutes or less at a reduced pressure so that the distillation column base temperature does not exceed about 85*C.

United States Patent Schirmann et a].

PROCESS FOR THE SEPARATION OF KETAZINES FROM THEIR CRUDE SYNTHESIS MIXTURES Inventors: Jean-Pierre Schirmann, Brignais; Marcel Thevenon, Pierre Benite, both of France Produits Chimiques Ugine Kuhlmann, Paris, France Filed: Dec. 18, I973 Appl. No.: 425,865

Assignee:

Foreign Application Priority Data Dec. 2|, I972 France .4 72.45576 US. Cl. 203/91; 203/37; 203/34; 260/566 B; 423/407 Int. Cl Btlld 3/10 Field oi Search 203/34-38, 203/50, 59, 91; 260/566 B; 423/407 Reierences Cited UNITED STATES PATENTS 3/1959 Nicolaisen 203/37 4, Hydrolysis Residence [451 May 13, 1975 3,012,948 l2/l96l Howitz et aI 203/59 3,527,753 9/l970 Needham et al. 260/566 B 3.728.390 4/l973 Jenkins et al. 260/566 B 3.773,83l ll/l973 Jefi'reys et aI. I. 260/566 B FOREIGN PATENTS OR APPLICATIONS 666,079 7/l963 Canada I. 203/59 Primary ExaminerNorman Yudkoff Assistant Examiner-D. Sanders Attorney, Agent, or FirmPennie & Edmonds [57] ABSTRACT This invention relates to a process for the separation by distillation of ketazines from a crude aqueous synthesis mixture containing them, which comprises adjusting the pH of the mixture to between about 8.5 and I2 by the addition of a base or an acid and distilling the crude reaction mixture during a period of 30 minutes or less at a reduced pressure so that the distillation column base temperature does not exceed about 85C.

3 Claims, I Drawing Figure Legend X= Examples I7, 18 a IS A- Examples u, l2, |3,|4 a. as

@Exomples a a a time, 50 minutes i I r I ll, l2, l3, l4 8 l5 =Exomples 8 a 9 Residence time, 30 minutes PROCESS FOR THE SEPARATION OF KETAZINES R FROM THEIR CRUDE SYNTHESIS MIXTURES R C BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the separation of ketazines and specifically to the separation by distillation of ketazines from crude reaction mixtures.

ll. Description of the Prior Art It is known that ketazines can be prepared by reactl0 ing chlorine or an alkali or alkali earth metal hypochlorite with ammonia and simple ketones such as acetone or methylethylketone to yield aqueous solutions containing the ketazines. The ketazines may be separated by distillation from the aqueous media, which are rich in mineral chlorides, and then hydrolyzed to form hydrazine and a ketone by using known methods. The intermediate formation of ketazines in these processes, which are derived from the Raschig process, thus offers a convenient means for separating hydrazine in a com- 5 in which R. and R each represent hydrogen or an alkyl radical of from 1 to 3 carbon atoms. The preferred kctones are acetone and methylethylketone.

However, it has been found that ketazines undergo premature hydrolysis of varying magnitude under these conditions, and it may result in the hydrolysis of as much as 50 percent of the ketazine present. This hydrolysis forms the hydrazone of the ketone or hydrazine itself, and these products can no longer be separated from the mixture containing salts or other abovementioned constituents by simple distillation. The hydrazine in fact forms, for example, an azeotropic mixture with water, the boiling point of which is higher than that of water; thus, it becomes concentrated in the residue during distillation. and its recovery from the residue becomes very difficult and costly.

bined form (kctazine) from the accompanying salts. SUMMARY OF THE INVENTION Anoth r gr up f gene a ynth es of azines has This invention relates to a process for recovering been disco ered d es e in previous Patent P- ketazines by considerably limiting the hydrolysis of the plications of common ownership to this application. ketazines by adjusting the pH of the crude reaction This group comprises oxidizing ammonia and a ketone media produced by known processes and by the aboveor an aldehyde by means of a peroxide compound acdisclosed processes to a value between about 8.5 and cording to the reaction 12 by the addition ofa suitable base when the pH of the R 3 R R 2 in which R and R represent a hydrogen atom or varimedium is too low or by the addition of a suitable acid ous hydrocarbon groups and in which 0 represents the when the pH of the medium is too high and by distillaactive oxygen of the peroxide compound or system tion of the crude reaction media during a period of 30 used. This formation of azines is consequently accomminutes or less at a reduced pressure so that the distillapanied by the formation ofa molecule representing the tion column base temperature does not exceed about product of the reduction of the oxidizing agent e 85C. In fact, the speed of hydrolysis of ketazines surployed. For example, an ammonium salt ofa carboxylic 4O prisingly passes through a marked minimum for the pH id i b i d h a b li id di values indicated, as is shown in the drawing which illus- U S. application S N 290,507, fil d S 20 trates the examples 7 to 19 described below.

1972), an l id di U apphcation S The process according to the invention comprises ad- No. 308,836. filed Nov. 22, 1972 or hydrogen peroxiusting y the addition of a base or an acid the p of ide in the presence of auxiliary reagents such as a car- 5 the Crude aqueous Synthesis mixture Containing? h box l t ester di U li i S zine to a value between about 8.5 and i2 and distilling 340 763 m d M 13 1973 or an amide f carbox the crude reaction mixture during a period of 30 minh id di s application Sch 3 5 utes or less at a reduced pressure so that the distillation fil d M 14 1973 i used; the product formed jointly column base temperature does not exceed about 85C. with the azine may be an amide if the oxidation took place with hydrogen peroxide and a nitrile of a carbox- DESCRIPTION OF THE PREFERRED ylic acid (French Pat. No. 70.21.704 of June I2, 1970, EMBODIMENTS and Pending application 152,413 filed The initial value of the pH of the crude synthesis mix- .lune ll, 1971). All of the above applications are of m d ed by the process of one of the abovecommon ownership to the Present appllcanon and are mentioned processes will determine whether it is necesincorporated herein by reference. In the processes dis- Sary to add a base, advtmtagttougy sdected f the closed in the above applications fractional distillation hydroxides or carbonates f alkali or alkali earth of the crude reaction mixtures is also an excellent als or an acid advantageously Selected f the means of separating the azines from the other constitu- 6O era] hydracids or oxyacids such as hydmchtotic acid, ents prior to hydrolyzing the azines with water to obtain Suhat-mc acid, phosphoric acid, the alky] or my] hydrazine, or with an acid to obtain a hydrazine salt. or hoxyhc acids or the a|ky| or ary] sulphonic acids h prior to using the azines directly as a synthesis intermei less h 20 carbon atgms f example, benzene diate. This separation is particularly easy with ketazines sulphonic acid),

prepared lower ketones OI thoseform The quantity of base 0 acid neces ary depend n azeotropic mixtures with water, the boiling point of the pH f the sohjtion to be treated and on the PH which is lower than that of Win61 itself- That is f y leeted for the distillation according to the process of though a large Choice of kelones aldehydes P the invention. This quantity will usually be between ble, it is advantageous for simplicity and economic reaabout 0.01 and 5 percent by weight of the reaction mixsons to use a lower dialkyl ketone of the formula ture, but more likely between about 0.1 and 2 percent by weight when producing a ketazine by one or more of the processes described in the above-mentioned applications. The base or acid may be added, where appropriate, directly into the fractional distillation col umn used for separating the ketazine. advantageously in the upper part of the column, into the feed stream of the column. or even into the immediately preceding synthesis reactor. The base or acid may be added in its pure state or in solution, such as, for example, in water.

The pH of the crude reaction mixture containing a ketazine is adjusted to a value between about 8.5 and I2. advantageously between 9 and l 1.

The distillation is carried out under reduced pressure so that the boiling point of the mixtures at the base of the distillation column does not appreciably exceed 85C. An advantageous pressure range is between 50 and 200mm Hg.

[t is advisable for the distillation to be carried out so that the residence time of the liquid phase in the col umn does not appreciably exceed half an hour and that the distillation column base temperature does not exceed 85C.

The following examples illustrate the present invention, but do not restrict it. The distillation was carried out in a glass apparatus.

EXAMPLES 1 to 6 The operation was carried out by discontinuous distillation using a residence time of 30 minutes. French Pat. No. 70.21.704 ofJune 12, 1970, and pending US. application Ser. No. 152,413, filed June 11, 1971, describe a method for preparing azines where at least one aldehyde or ketone or a mixture of at least one alde hyde and/or ketonc or ketones is reacted with ammonia and hydrogen perioxide in the presence of a nitrile to produce at least one azine. A reaction mixture resulting from the abovedescribed process where acetone was reacted with ammonia and hydrogen peroxide in the presence of acetonitrile was distilled under a reduced pressure of 50mm Hg to separate the acetone at the top of the distillation column. The composition by weight ofthe mixture was the following: ammonia 0.2 percent, acetone 6.5 percent acetonitrile 4 percent, acetonazine 27 percent, acetamide 18 percent, and water 36 percent. The operating conditions and the results are set out in Table l.

The acetonazine was determined by gas phase chromotography, and the whole of the N N groupings were determined by iodometry using the method of the French patent and pending U.S. application above where a quantity of reaction mixture containing about 2 milliequivalents of hydrogen peroxide was withdrawn from the reactor and weighed; 12 cm of aqueous sulphuric acid (30 percent by weight) and then 12 cm of aqueous potassium iodide (30 percent by weight) were added to the mixture; after standing for 15 minutes in darkness. the released iodine was titrated by a decinormal solution of sodium thiosulphate; 50 cm of a decinormal acqueous solution of iodine and then 30g of crystallized sodium acetate were added to adjust the pH of the sample to about 5', the sample was stirred and nitrogen evolved for about two minutes; and the excess iodine was titrated by a decinormal solution of sodium thiosulphate.

The percent of hydrolysis is defined by the formula chemistry azine chromato azine G hydrolysis chemistry anne TABLE 1 Ex. pH Pressure mm Hg T boiler 77' hydrolysis 1 11.1 50 Kl-41C 11.6 2 4.6 50 40-41 13 EXAMPLES 7 to 19 An Oldershaw distillation column with 30 plates of a diameter of 30 mm is continuously fed with the mixture previously described, for examples 1-6, at the rate of 200 mls. per hour. The mean residence time in the column may be fixed as desired by the quantity of liquid in the boiler, which is equipped with a continuous with drawal device. The distillation is carried out in such a way that the acetone and acetonitrile are eliminated at the top of the column. The operating conditions and the results obtained are set out in Table 11 below. The drawing shows particularly clear the minimum of the hydrolysis rates for the pH values between 8.5 and 12 in the case ofa residence time in the distillation column of 30 minutes at pressures of 50, 200, and 760mm Hg.

TABLE 11 Ex. Pressure Temperature pH Residence 71 Hydrolymm Hg of boiler time in sis "C mins.

7 760 104 9.5 I hr. 15 50.5 8 760 104 10.3 30 22 9 760 104 9.3 30 37 10 200 71 9.2 1 hr. 34 1 1 200 72 10.8 14 12 200 73 8.0 30 I3 200 74 9.1 30 28 14 200 73 10.4 30 I4 15 200 73 8.35 30 35 16 50 48 9.6 I hr. 15 20 17 50 47 t 1.1 30 18 18 S0 48 9 30 6.6 19 5O 6.8 30 20 EXAMPLES 20 to 22:

An Oldershaw distillation column as described above was fed with a mixture resulting from ammonia, hydro gen peroxide, acetone, and acetonitrile according to the process described above in pending U.S. application Ser. No. 152,413, filed June 11, 1971, but from which the ammonia and almost all the acetone and acetonitrile have been removed. its composition by weight is as follows. acetone 0.3 percent, acetonitrile 0.3 percent, acetonazine 31.0 percent, water 42.0 percent, acetamide 21.0 percent. The operating conditions and the results obtained are set out in Table I11.

TABLE 1]] Ex. Pressure Temperature pH Residence "4 Hydrolymm Hg of boiler time in sis C mins.

20 190 85 ll.(] 40 3.5M 21 1B0 85 (L2 40 ILKU 22 I40 82 b 40 I Ill) We claim:

1. A method for the separation of kctazines from a crude synthesis mixture containing them which com tilled under a reduced pressure of 50 to 200 mm Hg. 

1. A METHOD FOR THE SEPARATION OF KETAZINES FROM A CRUDE SYNTHESIS MIXTURE CONTAINING THEM WHICH COMPRISES ADJUSTING THE PH OF THE MIXTURE TO BETWEEN ABOUT 8.5 AND 12 BY THE ADDITION OF A BASE OR AN ACID AND DISTILLING THE CRUDE REACTION MIXTURE DURING A PERIOD OF 30 MINUTES OR LESS AT A REDUCED
 2. A method of claim 1 wherein the pH is brought to a value of 9 to
 11. 3. A method of claim 2 wherein the mixture is distilled under a reduced pressure of 50 to 200 mm Hg. 